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Surely there is no need for any of this complexity if properly designed - it can all come on at the same time, the slow rise of the heater will keep it all in check. A fuse protects against disasters. Can anybody post a schematic for a well designed amp that actually requires a delayed B+ ? I think you’ll be searching hard for exceptions if you can.
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since g2 voltage controlled cathode currents, having 0 volt g2 means cut off tube, tbh,i have not seen anybody do this anywhere, and i wonder why...
i have been toying with this idea for a long time now and i saw an online rc cal delay calculator wherein you can tailor the resistor capacitor combo to get you this delay...RC time constant / voltage calcultor
i think i may have an excuse to use this, i am doing a gk71 pentode single ended amp..
if you look at the tube datasheets and curves showing relations between plate, grid and g2 voltages, then it becomes an obvious possibility.....i am just wondering if any else have done it before....
perhaps PRR might want to chime in...
"Because it is so written in the Charter of the Service of Arms."
that would be the datasheet curves...
Receiving tubes at rated conditions: just turn them on. They were DESIGNED (and manufactured) for this.
An exception: Dynaco Mark VI has a delay relay.... *only* for the driver board, not the quad-team of power bottles.
https://hafler.com/pdf/dynaco/DynacoMarkVImanual.pdf
I sure do not think this is about "cathode-stripping" on the resistance coupled stages. My suspicion is that the turn-on thump which was mild on the 35W amps became very apparent on the 120+ Watt amp, and at the price, Dyna figured it was worth a delay-relay.
Not for Jan.
In Army everything must be Strong. Curves are not, they are approximate and average!
PRR's correct.
When manufacturers once relied on keeping their reputations in good standing, their products were built to strict standards, providing reliability, long life, and as little fuss as possible.
That was then...... and something that today is merely an afterthought, heavily overshadowed by greed.
Blame it all on multiple reasons...
I've seen the "changes" in the industry as the decades progressed, yet many seem to turn a blind eye to it, or be in denial of it.
The old, worn-out and tired already argument of " have you ever HAD these new products?" - "how can you be so judgmental?" crap cracks me up.
Because that's merely a "sticking up for" this new stuff.
"High End" today is merely a marketing term for glossy products with compen$ated rave reviewers.
I don't really mean to sound negative, honestly, but for sure I'll not mince words about things.
Perhaps someone might take heed and understand the whole mess, and choose sensibly.
I certainly didn't start the "vintage" campaign, people lusting for 1960's/70's products.
I imagine others sensed the real value of those things, and started the trend.
When manufacturers once relied on keeping their reputations in good standing, their products were built to strict standards, providing reliability, long life, and as little fuss as possible.
That was then...... and something that today is merely an afterthought, heavily overshadowed by greed.
Blame it all on multiple reasons...
I've seen the "changes" in the industry as the decades progressed, yet many seem to turn a blind eye to it, or be in denial of it.
The old, worn-out and tired already argument of " have you ever HAD these new products?" - "how can you be so judgmental?" crap cracks me up.
Because that's merely a "sticking up for" this new stuff.
"High End" today is merely a marketing term for glossy products with compen$ated rave reviewers.
I don't really mean to sound negative, honestly, but for sure I'll not mince words about things.
Perhaps someone might take heed and understand the whole mess, and choose sensibly.
I certainly didn't start the "vintage" campaign, people lusting for 1960's/70's products.
I imagine others sensed the real value of those things, and started the trend.
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Transmitting tubes are totally different from consumer-level tubes built for home use/audio.
And as such, they have much different operating procedures.
I just got a paper with an interview of a Philips tube designer, from 1991, from Guido Tent of Tentlabs fame (thanks Guido!).
It is in Dutch but it clearly delineates a mechanism where the cathode 'wears out' so to say when being brought up in temperature with B+ present. I really should translate it ...
Jan
It is in Dutch but it clearly delineates a mechanism where the cathode 'wears out' so to say when being brought up in temperature with B+ present. I really should translate it ...
Jan
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